Apparatus for shaping hollow metal bodies

ABSTRACT

Apparatus for shaping hollow metal bodies such as hollow rivets and the like on a mandrel including a hollow supporting sleeve adapted to receive the body and the mandrel. At least two forming bodies located in openings in the wall of the supporting sleeve, symmetrically with respect to the longitudinal axis of the sleeve. The forming bodies such as freely rotating balls or rollers with their external circumference against a pressure element surrounding at least in part the supporting sleeve and biasing the forming bodies against the surface of the hollow body.

United States Patent 1191 1111 3,924,434

Fulier Dec. 9, 1975 APPARATUS FOR SHAPING HOLLOW 1,919,869 711933Stanitz et al. 72/75 METAL BODIES 1,974,566 9/1934 Garrett 2,371,6973/1945 Logan 72/224 [75] Inventor: Josef Fuller, Nove Mesto nad VahomCzechoslovakla Primary Examinerl ;owell A. Larson [73] Assignee:Vyskumny ustav mechanizacie a L automatizacie, Nove Mesto nad ABSTRACTVahom, Czechoslovakia 2 Fl d: A Apparatus for shaping hollow metalbodies such as [2 1 1e pr 1974 hollow rivets and the like on a mandrelincluding a PP 463,915 hollow supporting sleeve adapted to receive thebody and the mandrel. At least two forming bodies located in openings inthe wall of the supporting sleeve, symliflE385:JJJJJJJJJJJJJJJJ:11:33:13???T 14331; 1213i liiiiiiilly will ii iiililgiililiiil ii iii 58 Field of Search 72/75 224 20s Sleeve- Theforming bodies such as freely rotating bans or rollers with theirexternal circumference against a [56] References Cited pressure lelementcsuli'roundinfig aft least inbpgrt the supporting s eeve an lasing t eorming o ies against UNITED STATES PATENTS the surface of the hollowbody. 629,245 7/1899 Frank 72/75 1,418,697 6/1922 Brinkman 72/75 10Claims, 5 Drawing Figures US. Patent Dec. 9 1975 3,924,434

APPARATUS FOR SHAPING HOLLOW METAL BODIES BACKGROUND OF THE INVENTIONThe present invention relates to an arrangement for shaping hollow metalbodies and particularly for shaping and forming hollow rivets, blind orone-sided rivets and the like.

Hollow rivets, particularly blind rivets must be shaped and formed ontheir external and internal surfaces with grooves, serrations, rachetteeth or the like in order that they assume the proper shape afterriveting and in order that they are capable of being grasped by themandrel of the riveting tool for blind insertion. In general hollowcylindrical workpieces are shaped after being placed over the pull ortear mandrel of the insertion tool by compressing the rivet betweensuitable dies. This operation occurs when the mandrel is fixed to theinsertion tool and fixes the body into the mandrel. Reference to mycopending application Ser. No. 335,747 filed Feb. 26, 1973, now US. Pat.No. 3,838,499, issued Oct. 1, 1974, will show such an arrangement. Thisprocedure has the disadvantage in that the dies needed to compress therivet while the mandrel is on the forming tool are rather complicatedand difficult to manufacture. Furthermore, their maintenance and repairis costly and uneconomical.

It is an object of the present invention to provide apparatus forshaping hollow metal bodies into rivets and the like in which thedrawbacks and disadvantages of the prior art are overcome.

It is a further object of the present invention to provide apparatus ofthe type described which would allow the formation of rivets and thelike from hollow metal bodies easily and efficiently.

It is a further object of the present invention to provide apparatus forshaping hollow metal bodies into rivets in which the apparatus is simpleand uncomplicated and which will permit the formation of rivets ofdifferent shape.

The foregoing objects, together with numerous other objects andadvantages, will be apparent from the following disclosure of thepresent invention.

SUMMARY OF THE INVENTION According to the present invention apparatus isprovided for forming hollow rivets and the like from hollow metal bodiescomprising a hollow cylindrical support. The support is provided with atleast two openings in its wall symmetrically arranged along thelongitudinal axis. A freely rotatable forming body is located in each ofthe openings so as to extend into the bore of the hollow support andoutwardly of the external surface of the support. A pressure element ismounted on the support so as to engage the external circumference of theforming body and to urge the forming body radially inward whereby oninsertion of a hollow metal workpiece and its supporting mandrel, theforming bodies roll over the external surface of the workpiece andcompress the same under pressure of the pressure element against themandrel.

The forming bodies can have the shape of balls or cylindrical rollerssuitably held in the openings by either shaping the openings orproviding the same with freely rotatable axles. The pressure element canbe a sleeve completely surrounding the cylindrical support and beingprovided with resilient spring means normally biasing the sleeve againstmovement but permitting movement in a direction opposite to that of themovement of the workpiece when the workpiece is inserted in theapparatus. The pressure element can also be formed as rollers fixedabout an axle secured to the cylindrical support and in contact with theforming element.

With the foregoing arrangement, the hollow workpieces can be shaped orreshaped along their longitudinal axis so as to obtain a modification ofthe profile of its cross section. The apparatus not only shapes theexterior surface but compresses the material against the mandrel holdingthe workpiece so that the inner surface is also shaped. The presentapparatus uses substantially smaller forces than those required fornormal die shaping. Another advantage of the present apparatus is that avariety of profiles and the degree of shaping of the internal andexternal surfaces can be achieved which surpasses that normally obtainedby the prior known apparatus.

Full details of the present invention are set forth in the followingdescription and in the accompanying drawing.

DESCRIPTION OF DRAWING In the drawing:

FIG. 1 is a longitudinal sectional view of apparatus for forming hollowrivets embodying the present invention,

FIG. 2 is a view similar to that of FIG. 1 showing a second embodimentof apparatus of the present invention,

FIG. 3 is a partial cross sectional end view showing the formation ofthe workpiece into the shaped rivet by the apparatus of FIG. 1,

FIG. 4 is a view similar to that of FIG. 3 showing the formation of therivet in accordance with the apparatus of FIG. 2, and

FIG. 5 is a partial longitudinal sectional view of the hollow workpieceand its supporting mandrel as it is being shaped by the apparatus ofeither FIG. 1 or 2.

DESCRIPTION OF PREFERRED EMBODIMENT In FIG. 1 one form of the presentinvention is shown comprising a hollow cylindrical supporting member 10having a bore 12. The supporting member 10 is provided with a conicaloutward flare 14 at its forward end and a radial outwardly directedflange 16 at its other end. The cylindrical support is further providedwith a pair of diametrically opposed holes 18 in each of which islocated a forming body which in the illustrated embodiment comprises aball 20. The holes 18 are shaped so as to retain the balls 20 and arearranged symmetrically with respect to the longitudinal axis of thesupport in a common transverse plane. The diameter of each of the balls20 is larger than the thickness of the wall of the cylindrical support10 so that its circumferential surface extends beyond the inner andouter surfaces of the support, i.e., into the bore 12 and beyond themantel of the support 10.

A cylindrical sleeve 22 having a radial outward flange 24 at its rearend surrounds the cylindrical port 10 and extends axially from theflared end 14 into abutment with the flange 16. The sleeve 22 has aninner diameter slightly larger than the outer diameter of thecylindrical support 10 but small enough to engage the circumferentialsurface of the balls 20 such that it is permitted to slide axially withrespect to the support 10 and to simultaneously exert a radial inwardpressure on the balls 20. Surrounding the sleeve 22 is a cylindricalcover 26 which'is threaded at its rear end to the flange 16 so as to bemaintained in fixed position. The cover 24 is provided with a radiallyinwardly directed flange 28 at its forward end. Arranged between theflanges 24 of the slidable sleeve 22 and the flange 28 of the cover 26is a spring 30 which acts to normally bias the slidable sleeve 22 in itsrearward direction. In forming a blind rivet or similar member, acylindrical hollow workpiece 32 is initially located over a pull or tearmandrel 34 having in the usual manner an inner diameter barely smallerthan that of the workpiece and having a contour conforming to thedesired shape to be given to the internal surface of the workpiece. Forexample, as seen in FIG. the mandrel is formed with a threaded portion36 and in FIGS. 3 and 4 with special cross sectional shapes. Variouscontours, shapes and threads may be provided in any desired combination.

The workpiece 32 and its mandrel 34 are simultaneously inserted into thefront or flared end of the bore '12 and pushed manually or mechanicallyin the direction of the arrow toward the rear end 16. As soon as theworkpiece contacts the surface of the balls 20 the balls start to turnand roll over the surface of the workpiece 32 and under the pressure ofthe pressure sleeve 22 form a longitudinal depression 38 on the outersurface simultaneously upsetting the material of the workpiece ,so thatits inner surface is compressed into the shape of the mandrel. As theballs 20 turn, moving counter clockwise, the pressure sleeve also beginsto move axially in a direction opposite to that of the moving workpieceand against the normal bias of the spring 30. This allows the balls 20to continue rolling while being urged radially inward with sufficientpressure to form the depressions 38. The workpiece may be movedcompletely through the support or it may be withdrawn after only partialpassage therethrough. In either event, the pressure sleeve 22 willreturn to its initial starting position as seen in FIG. 1; in the firstinstance under action of the spring 30, or in the second instance byrolling contact contrary to the movement of the workpiece and combinedwith the action of the spring. Due to the arrangement of the movablepressure sleeve 22 friction between the balls 20 and the sleeve and/orthe workpiece 32 is reduced to a minimum.

In FIG. 2 a modification of the apparatus according to the presentinvention is shown in which the pressure element rather than being asleeve completely surrounding the cylindrical support, comprises a pairof rollers 40 mounted about an axle 42 secured in a bracket 44 fixed tothe flange 16 of the support 10. The support being modified only to theextent to accommodate the bracket. As seen in FIG. 2 the axial length ofthe support may be chosen as desired in either embodiment. The operationof the apparatus according to FIG. 2 is similar to that described withregard to FIG. 1. The rotating pressure rollers reduce the frictionbetween the forrning bodies and the rollers and because they do not havea finite length as does the pressure sleeve 22 of FIG. 1, hollow metalbodies of longer length may be pulled or pushed through the bore.Further, the rollers 40 have no fixed directional bias and thusworkpieces can be pulled or pushed through the apparatus from either thefront or its rear ends. Workpieces can furthermore be fed sequentiallythrough the apparatus of FIG. 2 one after the other.

The number of forming bodies, such as the balls depend upon the exteriorshape which is to be given to the rivet. They may be in any desirednumber and of any desired diameter. As seen in FIG. 4 the forming bodiesmay be replaced by cylindrical rollers which provide a flat, rather thanan arcuate contour. In the apparatus of FIG. 2, if a small number offorming bodies are to be used, the apparatus may be further modified byutilizing the pressure rollers 40, in the shape of cylindrical rotatingrollers as the forming body, thereby eliminating one member of theapparatus. The pressure rollers 40 would then be mounted so as to extendthrough the openings 18 into contact with the face of the workpiece. Thecylindrical support 10 is suitably mounted on a frame or other device,not shown herein.

The arrangement according to the present invention is particularlyadapted for the formation of hollow metal rivets to conform to the pullor tear mandrel on which they are used. It is however possible to employthe present arrangement in other applications wherein recesses alonglongitudinal axes of hollow metal bodies have to be formed or where thewall of a hollow metal body should be shaped on its internal surface bymeans of an inserted mandrel or other inserted die. The presentinvention can also be used advantageously for the manufacture of avariety of nuts and similar devices each being formed from hollowcylindrical bodies.

Several modifications and changes have been described herein, othermodifications and changes will be obvious to those skilled in the art.It is therefore intended that the present disclosure be taken asillustrative only and not as limiting the present invention.

What is claimed is:

1. Apparatus for shaping hollow metal blind rivets comprising a hollowsupport having a cylindrical bore, at least one radial opening formed insaid support, forming elements rotatably arranged in said radialopenings and extending into said bore, an elongated mandrel forreceiving and axially inserting said rivets within said bore, saidmandrel having an outer contour v conforming to the desired shape ofsaid rivet, a'movable pressure element at least partially surroundingsaid support and engaging the external surfaces of the forming elementto conjointly roll therewith and to exert a radially inward force oneach movement of said mandrel and rivet through said bore, to cause saidforming elements to shape said rivet.

2. The apparatus according to claim 1 wherein th forming element isspherical.

3. The apparatus according to claim 1 wherein the forming elementcomprises a cylindrical roller.

4. The apparatus according to claim 1 wherein the pressure elementcomprises a sleeve surrounding said support and is provided withresilient means normally biasing said sleeve again st axial movement inone direction the movement of said rivet and mandrel through said bore,overcoming said bias. 1

5. The apparatus according to claim 4 including means for limiting theaxial movement of said sleeve in said one direction.

6. The apparatus according to claim 1 wherein the pressure element isformed by a rotating roller journalled on said support and rotatableabout an axis angular to the axis of the cylindrical bore.

7. The apparatus according to claim 1 .wherein said pressure elementcomprises a member movable with respect to both said forming element andsaid hollow support.

8. The apparatus according to claim 1 wherein said forming elements arefreely mounted within openings and being movable radially with respectto said support, said pressure element being spaced from the surface ofsaid support and limiting the outward movement of said forming element.

9. The apparatus according to claim 1 wherein the pressure element.

1. Apparatus for shaping hollow metal blind rivets comprising a hollowsupport having a cylindrical bore, at least one radial opening formed insaid support, forming elements rotatably arranged in said radialopenings and extending into said bore, an elongated mandrel forreceiving and axially inserting said rivets within said bore, saidmandrel having an outer contour conforming to the desired shape of saidrivet, a movable pressure element at least partially surrounding saidsupport and engaging the external surfaces of the forming element toconjointly roll therewith and to exert a radially inward force on eachmovement of said mandrel and rivet through said bore, to cause saidforming elements to shape said rivet.
 2. The apparatus according toclaim 1 wherein the forming element is spherical.
 3. The apparatusaccording to claim 1 wherein the forming element comprises a cylindricalroller.
 4. The apparatus according to claim 1 wherein the pressureelement comprises a sleeve surrounding said support and is provided withresilient means normally biasing said sleeve against axial movement inone direction the movement of said rivet and mandrel through said bore,overcoming said bias.
 5. The apparatus according to claim 4 includingmeans for limiting the axial movement of said sleeve in said onedirection.
 6. The apparatus according to claim 1 wherein the pressureelement is formed by a rotating roller journalled on said support androtatable about an axis angular to the axis of the cylindrical bore. 7.The apparatus according to claim 1 wherein said pressure elementcomprises a member movable with respect to both said forming element andsaid hollow support.
 8. The apparatus according to claim 1 wherein saidforming elements are freely mounted within openings and being movableradially with respect to said support, said pressure element beingspaced from the surface of said support and limiting the outwardmovement of said forming element.
 9. The apparatus according to claim 1wherein the contour of said mandrel conforms to that of the formingelements.
 10. The apparatus according to claim 1 wherein a plurality ofopenings are formed in the support, symmetrically with respect tolongitudinal axis, each having a forming element arranged therein and anassociated pressure element.